If your corn is not pretty dry it will spoil in the shipping container if you do not have any forced air ventilation. I tried to use them years ago to store ear corn and it was a mess. Half rotten corn is what I got.
As for the JD 4420 combine. They are a nice smaller combine. Pretty good with a 4x30 head.
As far as the price. I think that you will not see the $5 corn until after harvest if then. If we have a good harvest the days of $5,6 & $7 corn are over.
Nation wide and world wide the high corn prices has caused two things to happen.
1) The end users have switched to cheaper protein/starch sources. There is a lot of feed grade wheat now that was not there 3 years ago.
2) There is corn being raised in places that have not raised much corn before. They may not be raising 200 BPA corn but maybe they can make it on 50 BPA corn in that area. I read last Jan. that South Africa was exporting corn. That is not a normal export for them.